If I write a cautionary tale about the seductive evils of fascism,

with an unreliable narrator who's a cog in the evil machine, and obviously deluded about it,

and deeply unpleasant detailed descriptions of the awful cruelty perpetuated by the nazi regime,

and some fascists really like my book, because detailed descriptions of awful nazi cruelty are their jam, and they really identify with my evil, unreliable, deluded narrator

and a lot of people haven't read my book, but they know the kind of person who like my book - fascists

should I be judged by the popular reception of my work?

With this chain of events, at minimum you should be judged as someone who failed and accidentally created a fascist book.

But also, it is a bit suspect chain of events. Because it is quite unlikely that your books describe Jews in much sympathetic human way. Fascists would not like that. You wrote a book about suffering fascist and per your book ideology, fascism is bad when the fascists themselves suffer. That is just critique of concrete fascist regime from the point of view of the fascist.

Yes if your work encourages there to be more fascists